This invention relates to a method and an apparatus for transferring an electrostatic latent image.
In the xerography method, the electrofax method, and the like which are known as typical methods of image formation method by an electrophotography, it is well known that there is employed a method of directly visualizing or developing an electrostatic latent image using a coloring toner. Further, in an electronic copy machine of the transfer type, it is well known that a method is employed to transfer the toner image onto a transfer sheet to thereby obtain a reproduction or a duplication of the original image.
However, in the electronic copy machines of the transfer type constructed employing such a transfer system to transfer, onto a transfer sheet, a toner image obtained by developing an electrostatic latent image by a coloring toner, respective processes of the charging process, the exposure process, the development process, the transfer process, and the cleaning process are repeatedly applied to a photosensitive drum constituted by using a photoconductor, resulting in a shortened lifetime of the photosensitive drum. To overcome this drawback, an attempt has been made to carry out a method for transferring an electrostatic latent image. Hitherto, various methods for transferring an electrostatic latent image have been proposed.
Meanwhile, in the conventional system for transferring an electrostatic latent image, an electrostatic latent image is transferred then developed by using a coloring toner, where an absolute value of the electrostatic potential of the transferred electrostatic latent image is unnecessary to be concerned.
However, in the high resolution image pickup device such as disclosed in the European Patent Application No. 89300633.8 filed by the applicant of the present application, it is dependent upon the absolute value of potential of an electrostatic latent image for reading out the electrostatic latent image as a video signal. In view of this, a method which can be readily put into practice has not been known in the art.